Monolithic integrated four DFB lasers array with a polymer-based combiner for WDM applications

Compact and low cost integrated photonic components will be of significant importance for a wider penetration of optical technologies into private customer access systems. Hybrid semiconductor/polymer integrated technologies are very promising to achieve this goal by virtue of the highly flexible nature of polymers at both molecular and material scale, of their compatibility with processing steps used in semiconductor technologies, and of their reasonably low cost. One example is an integrated semiconductor 4-wavelength laser array with a polymer based 1–4 passive optical combiner on the same substrate. The polymer waveguide structure is a polysulfone material stripe embedded in PMMA cladding layers, and the laser structure is a buried ridge stripe (BRS). The optical coupling between the active and passive elements is a butt-joint coupling via a reactive ion beam etched (RIBE) semiconductor mirror facet. Such a photonic integration simplifies the optical coupling between a laser array and single mode fibers, while reducing the packaging cost. This optical device has been achieved with interesting performances such as small dimension size (1.2 × 0.5 mm), low laser threshold current, and output powers for each laser from the polymeric waveguide port of at least 1.5 mW without additional on-chip optical amplification.     

Learning and recall algorithm for optical associative memory using a bistable spatial light modulator

A learning and recall algorithm for optical associative memory based on the conventional correlationlearning method with three effective improvements (sparse-encoding method, constant-total-activity method, and binary memory) is proposed from a viewpoint of practical implementation. It is shown that the algorithm is suitable for implementation with a bistable spatial light modulator such as a ferroelectric liquid-crystal spatial light modulator, which has high resolution and a fast response time. The results of theoretical analysis and simulations indicate that the algorithm permits an associative-memory system with a large memory capacity to be realized. An example of an optical system for executing this algorithm is proposed. To determine the performance specifications that are required for the various optical components within the system, we simulate and evaluate the effect of noise (which is caused by nonideal components) on system performance. These results show that the system is robust in the presence of predicted noise levels.     

Concept of a miniature optical spectrometer using integrated optical and micro-optical components

We describe the concept of a super compact diffractive imaging spectrometer, with optical components a few millimeters across in all dimensions, capable of detecting optical fluorescence spectra within the entire visible spectral range from 400 nm to 700 nm with resolution of the order of 2 nm. In addition, the proposed spectrometer is capable of working simultaneously with multiple, up to 35, independent input optical channels. A specially designed diffractive optical element integrated with a planar optical waveguide is the key component of the proposed device. In the preliminary experimental tests, a uniform waveguide grating with a microlens was used to mimic operation of the diffractive optical element. A microspectrometer with optical components measured below 1 cm in all dimensions covers the spectral range from 450 nm to 650 nm and shows a spectral resolution of 0.5 nm at wavelengths close to 514 nm and 633 nm.     

Orthogonal aperture multiplexing for multilayered waveguide holographic read-only memories

A multilayered waveguide holographic read-only memory is a promising candidate for the next generation of optical data storage systems. We improved the data density of the memory by using a multiplexing method with a set of orthogonal optical masks. We multiplexed as many as nine images into one waveguide hologram, and all the observed images had negligible cross talk. This made it possible to achieve a ninefold increase in data density. We provide experimental results for both metallic and liquid-crystal masks.     

Focusing characteristics of a planar solid-immersion mirror

The focusing characteristics of a planar waveguide solid-immersion mirror with parabolic design have been investigated. The solid-immersion mirror is integrated into an optical waveguide, and light focusing is achieved with a parabolic mirror parallel to the waveguide plane and waveguide mode confinement normal to the waveguide plane. Optical-quality tantala silica planar waveguides can be obtained by evaporation. The parabolic sidewall reflects over 50% of the incident waveguide mode and generates a diffraction-limited focus. The measured spot size for the solid-immersion mirror described here is less than one third of the wavelength. Polarization analysis shows that the electric field near the focal region has components parallel and normal to the polarization state of the incident beam. The planar solid-immersion mirror is essentially free of chromatic aberration, and the alignment of the illumination beam is within a fraction of degrees.     

Integrated optical motor

A light-driven micrometer-sized mechanical motor is created by laser-light-induced two-photon photopolymerization. All necessary components of the engine are built upon a glass surface by an identical procedure and include the following: a rigid mechanical framework, a rotor freely rotating on an axis, and an integrated optical waveguide carrying the actuating light to the rotor. The resulting product is a most practical stand-alone system. The light introduced into the integrated optical waveguide input of the motor provides the driving force: neither optical tweezers or even a microscope are needed for the function. The power and efficiency of the motor are evaluated. The independent unit is expected to become an important component of more complex integrated lab-on-a-chip devices.     

Multilayered optical memory with bits stored as refractive index change. I. Electromagnetic theory

With the Lippman-Schwinger equation, dyadic Green's functions, and the vector coherent transfer function method, an electromagnetic theory of a waveguide multilayered optical memory is first developed for the static case, from which a theory describing a conventional multilayered optical memory with bits stored as a refractive index change is also derived. In addition, the formulas for readout signals and cross talk are given, and some problems of numerical calculations are discussed. The theories can be used effectively for optimum design of a multilayered optical memory with bits stored as a refractive index change.     

Optoelectronic-cache memory system architecture

We present an investigation of the architecture of an optoelectronic cache that can integrate terabit optical memories with the electronic caches associated with high-performance uniprocessors and multiprocessors. The use of optoelectronic-cache memories enables these terabit technologies to provide transparently low-latency secondary memory with frame sizes comparable with disk pages but with latencies that approach those of electronic secondary-cache memories. This enables the implementation of terabit memories with effective access times comparable with the cycle times of current microprocessors. The cache design is based on the use of a smart-pixel array and combines parallel free-space optical input-output to-and-from optical memory with conventional electronic communication to the processor caches. This cache and the optical memory system to which it will interface provide a large random-access memory space that has a lower overall latency than that of magnetic disks and disk arrays. In addition, as a consequence of the high-bandwidth parallel input-output capabilities of optical memories, fault service times for the optoelectronic cache are substantially less than those currently achievable with any rotational media.     

光波导触觉传感系统中的导波模式理论分析

根据光波导触觉传感系统受压时所形成的四个光斑面积大小,可求出作用于系统的xyz三向力。利用导波模式理论,当系统受外力时,平面波的全内反射条件遭到破坏,半圆球触头与波导板的接触部分由对称平面波导转变为非对称平面波导,造成光泄漏,形成光斑,其频率范围在对称平面波导的截止频率和非对称平面波导的截止频率之间。     

Novel system for coupling to surface-plasmon polaritons

A novel system for coupling to surface-plasmon polaritons has been designed, fabricated, and assembled. Microcomputer controlled electronics provide for accurate and repeatable angular positioning of the waveguide coupler with respect to the incident beam and for precise angular registration of detector output signals. The optical components, combined with a retroreflecting spherical-surface coupling prism, give apertured control of the beam profile at the coupling interface.     

Tissue culture system using a PANDA ring resonator and wavelength router for hydroponic plant

A novel system of nanofluidics trapping and delivery, which is known as a tissue culture system is proposed. By using the intense optical pulse(i.e., a soliton pulse) and a system constructed by a liquid core waveguide, the optical vortices (gradient optical fields/wells) can be generated, where the trapping tools in the same way as the optical tweezers in the PANDA ring resonator can be formed. By controlling the suitable parameters, the intense optical vortices can be generated within the PANDA ring resonator, in which the nanofluidics can be trapped and moved (transported) dynamically within the Tissue culture system(a wavelength router), which can be used for tissue culture and delivery in the hydroponic plant system.     

Analysis of far-infrared horns, lightpipes, and cavities containing patterned conductive films

A scheme is described for calculating the scattering parameters of patterned conductive films in waveguide. The films can have non-uniform, non-isotropic, and non-local sheet impedances. Once the scattering parameters are known, they can be combined with the scattering parameters of paths, dielectric slabs, and waveguide steps to build up models of complicated components comprising patterned films in profiled lightpipes and cavities. It is then straightforward to calculate the Stokes fields of the total reception pattern, the natural optical modes to which the component is sensitive, the Stokes fields of the individual natural modes, and the spatial state of coherence. The method is demonstrated by modeling an absorbing pixel in a length of shorted multimode waveguide. The natural optical modes change from being those of the waveguide to those of a free-space pixel as the size of the absorber is reduced.     

Application of the transmission line matrix method to the analysis of slab and channel optical waveguides

The applicability of the three-dimensional vectorial transmission line matrix (TLM) method to the analysis of optical waveguiding structures is demonstrated. Any waveguide geometry, even incorporating anisotropic materials, can be treated by taking into account the coupling between all optical field components. The application of the TLM method to optical waveguides is shown to be both efficient and accurate. The dispersion curve for the fundamental TE-like mode of a typical rib dielectric waveguide as well as its electric-field pattern is obtained by the use of the TLM method. Numerical comparisons with the integral-formulation technique, the effective-index method, the finite-difference analysis, the spectral-index method, and the beam-propagation technique are also included.     

Liquid/liquid optical waveguides using sheath flow as a new tool for liquid/liquid interfacial measurements

A liquid/liquid optical waveguide was constructed using a sheath flow. Since the refractive index of an organic solvent is generally higher than that of water (nD = 1.33), light introduced into the inner organic flow should proceed with total multi-reflection within the inner flow, so that the inner part of the sheath flow acts as the core of an optical waveguide. This sheath flow liquid/liquid optical waveguide was stable and showed no substantial background scattering. Moreover, it is applicable to both miscible and immiscible liquid/ liquid interfaces. Thus, it may become a new tool for studying liquid/liquid interfaces as well as for sensitive optical measurements.     

扩束光纤与宽波导光栅的光耦合特性

为了研究光纤与宽波导光栅的有效耦合,基于高斯光束与波导光栅的光耦合理论,以30μm宽波导光栅为研究对象,利用矩阵光学和高斯光束理论分析和设计了一种扩束光纤,并通过分析其耦合损耗,建立了扩束光纤与波导光栅耦合模型.优化所设计扩束光纤的结构参数后,得到束腰半径为10.8μm的输出光束.最后分析了扩束光纤的结构容差,并讨论了所设计扩束光纤的输出光束、单模光纤的输出光束以及束腰半径为16 μm的自由空间高斯光束各自在光栅表面的位置变化对光栅耦合效率的影响.可知扩束光纤输出的光束与单模光纤输出的光束相比具有较大的位置容差,与束腰半径为16 μm的自由空间高斯光束相比,光耦合效率基本相同.     

Tunable microring resonator based on dielectric-loaded surface plasmon polariton waveguides

Integrated optical ring resonators are essential elemental components for integrated optical circuits. An ultrasmall thermo-optical microring resonator with two bus waveguide-configuration based on surface plasmon polariton waveguide is theoretically analyzed. The thermo-optical coefficient, the temperature-dependent amplitude attenuation coefficient and the temperature distribution properties of the waveguide are investigated numerically by finite element method. The critical resonant conditions of the microring resonator are discussed by considering the propagation losses in the plasmonic ring cavity. The transmission characteristics and the tunability of the ring resonator with different structural parameters are investigated. The results show that the proposed ring resonator with a low driving power and high efficient tunability has potential to develop nano-scope wavelength tunable channel drop filters, low power optical switches, attenuators, and other high compact integrated optical devices.     

Optical forces in hybrid plasmonic waveguides

We demonstrate that in a hybrid plasmonic system the optical force exerted on a dielectric waveguide by a metallic substrate is enhanced by more than 1 order of magnitude compared to the force between a photonic waveguide and a dielectric substrate. A nanoscale gap between the dielectric waveguide and the metallic substrate leads to deep subwavelength optical energy confinement with ultralow mode propagation loss and hence results in the enhanced optical forces at low input optical power, as numerically demonstrated by both Maxwell's stress tensor formalism and the coupled mode theory analysis. Moreover, the hybridization between the surface plasmon modes and waveguide modes allows efficient optical trapping of single dielectric nanoparticle with size of only several nanometers in the gap region, manifesting various optomechanical applications such as nanoscale optical tweezers.     

Waveguide properties of optical structures fabricated by oxidation of porous silicon

Results of an investigation of the optical properties of channel waveguides fabricated by oxidation of porous silicon are described. The waveguide parameters are estimated and the existence of optical anisotropy is established. The effective refractive index of the dominant quasi-TM waveguide mode is measured. The results suggest that a buffer layer exists between the waveguide and the silicon substrate. It is hypothesized that a second refractive index peak exists within this layer. Pis’ma Zh. Tekh. Fiz. 23, 86–89 (May 26, 1997)     

Waveguide lasers based on dielectric materials

Fifty years since the invention of the laser have been witness of the development of many different laser systems and designs. Among them, miniaturized versions of solid sate lasers based on rare-earth-doped dielectric materials have been proposed and demonstrated during the last 20 years. They are based on confined radiation provided by optical waveguide structures. Although many materials and techniques have been studied for producing planar and channel waveguides, only a few of them have shown to be adequate routes for fabricating waveguide lasers. Here we summarize the theory and specific technologies developed for characterizing waveguide structures, and we present some common fabrication techniques already successfully applied to fabricate dielectric waveguide lasers, where relevant examples of demonstrated working devices are outlined.     

Fiber-optic chemical sensing with langmuir-blodgett overlay waveguides

Fiber-optic chemical sensing has been demonstrated with a side-polished single-mode optical fiber, evanescently coupled to chemically sensitive Langmuir-Blodgett (LB) overlay waveguides. The sensors exhibit a channel-dropping response centered on a wavelength that is dependent on the thickness and the refractive index of the overlay waveguide. It has been shown that pH-sensitive organic dyes proved to be suitable materials for the formation of an overlay waveguide whereas LB deposition provides the required thickness control. A theoretical model of the sensor response, based on the Kramers-Kronig relations and phase matching of the guided modes within the optical fiber and overlay waveguide, shows good agreement with experimental results.